The present invention relates to a miniature, beam-type multi-mode accelerometer. Accelerometers of this kind respond to shock in several different directions. The present invention is especially useful on disk drives of notebook-size computers, and on other shock-sensitive, portable or hand-held equipment.
The present invention is directed to increasing the sensitivity, accuracy and compactness of such an accelerometer, and is further directed to reducing the cost of its manufacture.
The multi-mode accelerometer described herein operates in one or more linear modes along X and Z axes which are orthogonally disposed, i.e., in a common plane at right angles to one another, and also in an angular or torsional mode about the Z axis. The present accelerometer is operable in one or several of such modes.
Notebook size computers employ small-diameter hard disk drives for data storage, that is, the information is magnetically stored on closely spaced tracks of rotatable discs. In the event that the disk drive experiences shock during the read/write operation, an improper read or write to the disk may take place; and an accelerometer is employed to detect the shock and initiate a response. A multi-mode accelerometer constructed according to the present invention initiates an interruption of the read/write operation in response to shock above a predetermined level in one or more of the modes previously described. In addition, the accelerometer signal may be used in a feedback loop to control the position of the read/write arm, such as to reverse or otherwise reposition the arm in the event of shock. Furthermore, the accuracy, dependability, low cost, and thumbnail size of the accelerometer herein-described is well suited for advanced hard drive and notebook-size computer apparatus.
Although a multi-mode accelerometer is disclosed herein, it may be configured advantageously to respond solely to torsional mode acceleration. Such a single mode accelerometer will be less expensive to manufacture, and the complexity and cost of electrical interfacing will also be reduced.
The construction of the disc drive shown and described in U.S. Pat. No. 4,831,476, issued May 16, 1989 to P. J. Pisczak, is incorporated herein by reference for the sake of brevity in disclosing apparatus of the type with which the present invention is operatively associated and has its principal utility.